Image-acquisition apparatus for performing distance measurement using parallax

Abstract

Provided is an image-acquisition apparatus including an image-acquisition lens that collects light coming from a subject A; an image-acquisition device that acquires images with the light collected by the image-acquisition lens; a microlens array that is disposed between the image-acquisition device and the image-acquisition lens; and a distance calculating portion that calculates a distance to the subject by using information obtained by the image-acquisition device. The microlens array has multiple types of microlenses, for different polarization states, that focus light incident thereon to form individual images on an image-acquisition surface of the image-acquisition device and that are arranged in an array in directions orthogonal to an optical axis thereof, and the distance calculating portion calculates the distance by performing matching processing in which each polarization state is weighted according to frequency components of the information obtained by the image-acquisition device.

The invention claimed is: 
     
       1. An image-acquisition apparatus comprising:
 an image-acquisition lens that collects light coming from a subject; 
 an image-acquisition device that acquires an image with the light collected by the image-acquisition lens; 
 a microlens array that is disposed between the image-acquisition device and the image-acquisition lens, that includes a plurality of types of microlenses with different polarization states arranged in an array in directions orthogonal to an optical axis of the microlens array, and that focuses light incident on the microlens array from the image-acquisition lens to form individual images on an image-acquisition surface of the image-acquisition device; and 
 a distance calculating portion that calculates a distance to the subject by using information obtained by the image-acquisition device; 
 wherein the image-acquisition device acquires images of the light focused by the microlens array to obtain image signals having a plurality of polarization states, 
 wherein the distance calculating portion calculates the distance to the subject by using parallax calculated by performing matching processing of a pixel included in a pixel region corresponding to one of the plurality of types of microlenses and a pixel included in a pixel region corresponding to another one of the plurality of types of microlenses, and 
 wherein, in the matching processing:
 for brightness information of an image signal obtained by the image-acquisition device, an edge quantity for each of the plurality of polarization states is calculated for each pixel; 
 a weighting coefficient is decided based on the edge quantity for each of the plurality of polarization states; and 
 the weighting coefficient is set to a larger value as a magnitude of the edge quantity increases, and the weighting coefficient is set to a smaller value as the magnitude of the edge quantity decreases. 
 
 
     
     
       2. The image-acquisition apparatus according to  claim 1 , wherein the image-acquisition device is a color image-acquisition device in which a plurality of color filters are arrayed on the image-acquisition surface thereof in regions corresponding to individual microlenses. 
     
     
       3. The image-acquisition apparatus according to  claim 1 , wherein the distance calculating portion performs the matching processing on pixel regions corresponding to microlenses that are in a vicinity of the one of the plurality of types of microlenses. 
     
     
       4. The image-acquisition apparatus according to  claim 1 , wherein the distance calculating portion performs the matching processing on pixel regions corresponding to microlenses that are adjacent to the one of the plurality of types of microlenses. 
     
     
       5. The image-acquisition apparatus according to  claim 1 , wherein:
 the plurality of the polarization states are four polarization states; and 
 polarization directions of the four polarization states are different from each other.